Which smear finding is characteristic of immune-mediated hemolytic anemia?

• A. Spherocytes on smear
• B. Heinz bodies
• C. Howell-Jolly bodies
• D. Target cells

Answer: (A)

Red blood cell membrane loss caused by antibodies binding to the cell leads to extravascular destruction, mainly in the spleen. As the membrane is stripped away while hemoglobin remains, the cells shrink and become spherical. These spherocytes appear on a peripheral smear as small, dense cells with reduced or absent central pallor. That change specifically reflects the mechanism of immune-mediated hemolysis: loss of membrane without a proportional loss of hemoglobin, producing the characteristic spherical shape.

Other findings point to different processes: Heinz bodies are inclusions from oxidative damage to hemoglobin; Howell-Jolly bodies are nuclear remnants seen with splenic dysfunction; target cells appear with altered membrane-to-volume ratio in liver disease or certain anemias.